Eriko is an ordinary housewife who lives peacefully with her husband, daughter, and son-in-law Hiroaki. Her peaceful daily life is Eriko's treasure. One day, Eriko has an affair with a young man from her part-time job, and Hiroaki witnesses it. Eriko begs him to keep it a secret, which stimulates Hiroaki's Kokoro tendencies, and he grabs Eriko's huge breasts. The two of them become immersed in forbidden pleasure.